#include <sys/mman.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>


static void *alloc_arena_shm(size_t arena_size, unsigned flags)
{
	FILE *fh;
	char buf[512];
	size_t huge_page_size;
	char *p;
	int shmid;
	void *arena;

	// find Hugepagesize in /proc/meminfo
	if ((fh = fopen("/proc/meminfo", "r")) == NULL) {
		perror("open(/proc/meminfo)");
		exit(1);
	}
	for (;;) {
		if (fgets(buf, sizeof(buf)-1, fh) == NULL) {
			fprintf(stderr, "didn't find Hugepagesize in /proc/meminfo");
			exit(1);
		}
		buf[sizeof(buf)-1] = '\0';
		if (strncmp(buf, "Hugepagesize:", 13) == 0) break;
	}
	p = strchr(buf, ':') + 1;
	huge_page_size = strtoul(p, 0, 0) * 1024;
	fclose(fh);

	// round the size up to multiple of huge_page_size
	arena_size = (arena_size + huge_page_size - 1) & ~(huge_page_size - 1);

	shmid = shmget(IPC_PRIVATE, arena_size, IPC_CREAT|IPC_EXCL|flags|0600);
	if (shmid == -1) {
		perror("shmget");
		exit(1);
	}

	arena = shmat(shmid, NULL, 0);
	if (arena == (void *)-1) {
		perror("shmat");
		exit(1);
	}

	if (shmctl(shmid, IPC_RMID, 0) == -1) {
		perror("shmctl warning");
	}

	return arena;
}

int main(int argc, char **argv)
{
        char buf[1024];
        const size_t sz = 64*1024*1024;
        void *arena = alloc_arena_shm(sz, SHM_HUGETLB);
        memset(arena, 0, sz);
        snprintf(buf, sizeof(buf), "grep ^%llx /proc/%d/numa_maps", (unsigned long long)arena, (int)getpid());
        system(buf);

        arena = alloc_arena_shm(sz, 0);
        memset(arena, 0, sz);
        snprintf(buf, sizeof(buf), "grep ^%llx /proc/%d/numa_maps", (unsigned long long)arena, (int)getpid());
        system(buf);

        return 0;
}